Aspirating agitator for dispersing nonaqueous solution in aqueous gelatin solutions

ABSTRACT

This invention relates to a mixing apparatus for dispersing small amounts of liquids in bulk liquids with substantial elimination of coagulation caused by low dispersion rates of portions of the added liquid. In one aspect this invention relates to a mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

United States Patent [72] Inventors ".iomin A. Johnson; 2,635,860 4/1953 McLeod 259/23 Donald 2,971,748 2/196] Ellegast 259/96 213 2 1968 Primary Examiner-Robert W. Jenkins mvisionof No. 355.703, Man 30, 1964, AttorneysW. H. J. Kline, Bernard D. Wrese and Gerald E. Pat. No. 3425.335 [45] Patented Mar. 16, 1971 [73] Assignee Eastman Kodak Company Rochester, N.Y.

7 ABSTRACT: This invention relates to a mixing apparatus for [54] ATIN dispersing smallarnounts of liquids in bulk liquids with sub- SOLUTIONS stantial elimination of coagulation caused by low dispersion 13 Claims 4 Drawin E 5 rates of portions of the added liquid. in one aspect this inveng g tion relates to a mixing apparatus which comprises a rotatable [52] US. Cl 259/22 haft having at one end a propeller agitator composed of Cl /0 blades, said blades encased in a funnel-shaped tubular confin- [50] Field of Search 259/l4, l5, ing means, means positioned at the larger end of said funnel- 16, 22, 23,24, 95,96, 97, 2l,40,4l,42,43,44, shaped confining means to form an annular opening, means 106, 107, 108; 96/94 for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the in- [56] References cued terior of said confining means, at a point at which the liquid in UNITED STATES PATENTS bulk amount enters, a second liquid in an amount compara- 2,501,467 3/1950 Ittner 259/23 tively small relative to the liquid in bulk amount ATENTEU MAR 1 s |97| INVENTORS BENJAMIN A. JOHNSON DONALD M. FORSTER A TTORNEY ASPIRATING AGITATOR FOR DISPERSING NONAQUIEGUS SOLUTION IN AQUEOUS GELATIN SOLUTIONS This application is a divisional application and a continuation-in-part of US. Ser. No. 355,703 filed Mar. 30, 1964 now US. Pat. No. 3,425,835 issued Feb. 4, 1969.

This invention relates to a method of dispersing water-miscible liquids in hydrophilic colloid solutions and an apparatus useful for this purpose.

In the making of gelatin compositions for use in photographic manufacture and especially photographic emulsions, it is frequently desirable to introduce chemicals therein which must be dissolved in water-miscible nonaqueous solvents before they are incorporated in the aqueous gelatin solutions. Some materials which are often introduced into photographic gelatin coating solutions or photographic emulsions are dyes, sensitizers, hardeners, antifoggants, stabilizers, etc. Often compounds of this nature which are most effective are preferably introduced into the gelatin compositions in the form of their solutions in nonaqueous organic solvents. The introduction of such solvents into gelatin compositions often cause local dehydration of the gelatin resulting in particulate matter which cannot be readily redispersed in the gelatin composition. Such particulate matter may subsequently cause defects in film prepared using these photographic gelatin compositions.

Various procedures have been suggested for minimizing the dehydration of gelatin as, for example, by adding the nonaqueous solvent solution very slowly to the surface of the gelatin composition while the bulk of that composition is being agitated by a rotating impeller within a vessel. Various nozzles and spreading devices have been considered for use in dispensing the solvent before it contacts the surface of the batch. Foam on the surface of such compositions if contacted by such solvents is particularly susceptible to dehydration due to the unfavorable solvent concentrations therein. None of the previous proposed methods have been sufficiently effective in minimizing product degradation form visible defects in the product from insoluble particles. Filtering the final solution is inadequate for eliminating those defects.

One object of our invention is to provide a method of incorporating nonaqueous solutions into aqueous gelatin composi' tions avoiding dehydration of the gelatin contained in the bulk solution. Another object of our invention is to provide a method of incorporating nonaqueous solutions into aqueous gelatin compositions which avoids contact with the surface foam of the gelatin composition, foam being especially sensitive to dehydration. A further object of our invention is to provide a method of mixing nonaqueous solutions and aqueous gelatin compositions eliminating manual lifting and pouring from containers. A still further object of our invention is to provide an apparatus which is useful in embodying the procedure for incorporating nonaqueous solvent solutions into aqueous gelatin compositions in the manner described herein. Other objects of our invention will appear herein.

In accordance with our invention, nonaqueous solutions are incorporated into aqueous gelatin compositions by aspirating the nonaqueous solutions from an external container into a batch consisting of an aqueous gelatin solution as it is rapidly dispersed and mixed by means of a rotating propeller encased in a shell having a funnel-shaped tubular confining means. The rapidity of mixing at the point of entry of the nonaqueous solution prevents local concentrations causing dehydration of the gelatin so that few, if any, insoluble particles are created. Our invention involves the circulation of an aqueous gelatin composition into a highly agitated confined premixing area into which a small stream of nonaqueous solution is being fed which is then dissipated into the bulk gelatin solution by means of an annular discharge space.

The procedure in accordance with our invention may more readily be described by referring to the novel apparatus in which the introduction of the nonaqueous solvent solution into the aqueous gelatin composition is carried out.

In one embodiment this invention generally relates to a mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

We have found that with the mixing apparatus of this invention we are able to obtain rapid mixing of small additive liquids into bulk liquids with virtually no coagulation due to low dispersion rates.

In the accompanying drawings:

FIG. 1 illustrates, in section, apparatus in accordance with the invention in use in a container for the bulk gelatin solution.

FIG. 2 is a drawing in section of an impeller in accordance with the invention in which the shell of the impeller rotates.

FIG. 3 is a view in section taken through line 3-3 of FIG. 2 showing the structure of the collar employed in FIG. 2.

FIG. 4 is an illustration in section taken through 4-4 of FIG. 2 showing the arrangement of the impeller blades within the aspirating agitator of FIG. 2.

In FIG. 1 a driving means for the impeller, in this case an electric motor 1, is attached to the vessel 8, which contains the gelatin solution, by means of a tubular support and bracket 2. Shaft 3, which is an axial extension of thedrive shaft of motor 1, is attached to agitator blades within shell 4 to which the agitator blades are attached whereby'the shell rotates upon rotation of the blades by shaft 3. Also fastened to driving means 1 is a hollow support tube 5 attached to the motor by means of clamps (or some other type of fixture) 6. At the other end of the support tube 5 is nozzle 7 so positioned that liquid passing through tube 5 is introduced into the space confined by shell 4. The rotation of the impeller blades creates movement of the liquid contained in the vessel 8 whereby the liquid enters the shell 4 in the narrow neck portion thereof and exits through an effluent annulus on the bottom of shell 4. The shell or confining means can generally be of a diverging tubular shape such as a funnel-shaped device. In one preferred embodiment, the confining means are in the shape of a truncated cone. In another preferred embodiment, the confining means can have cylindrical tubular segments as long as the overall macroscopic shape of the confining means is a diverging wall tubular shape such as, for example, a confining means as shown in FIG. I. Confining means in the shape of a truncated pyramid can also be used when the agitator blades move relative to the shell. In another preferred embodiment, the inlet 7 for the additive liquid is located within a conic sectional opening at the diverging end of said confining means as shown, for example, in FIG. I. The confining means can be provided with vanes disposed internally and substantially parallel to the shaft to counteract vortexing or direct effluent material. Vessel 8' may desirably be provided with a baffle 9 which can be varied in size and placed in a variety of positions in the vessel. Vessel 8 is also provided with an outlet 10 whereby the contents of the vessel 8 may be removed when and if desired.

FIG. 2 shows in detail one design of an aspirating agitator useful in incorporating nonaqueous solvent solutions into aqueous gelatin solution in accordance with the invention. In FIG. 2 the unit composed of blades 15 is held on shaft 13 by wingnut l7 so that rotation of shaft 13 causes rotation of the blades or paddles. In FIG. 2 the blades are joined to shell 14 whereby the blades and the shell rotate together. Held on the end of the shaft by wingnut 17 is a disc 16 restricting the bottom of the shell to an effluent annulus. The disc is preferably in abutting relationship with the sides of the blades. The effluent opening can also take the form of holes or slots posi tioned in the side of the confining means near the larger end of the diverging walls to provide an opening substantially annular the collar are more clearly illustrated in FIG. 3 which shows.

inlet 19 which leads into the space between collar 18 and the shaft 13 where the nonaqueous solvent solution comes in contact with the aqueous gelatin solution flowing through sleeve 20 into the confined area within shell 14 in which agitation occurs.

The setup of apparatus within the shell is more clearly illustrated by HG. 4, which shows the arrangement whereby the rotatable blades 15 are affixed on the shaft and the attachment of the blades 15 to the shell 14. Instead of the shell rotating with the blades, modification of our invention involves the blades being not attached to the shell which is held stationary such as by being attached to one or more supports such as tube in FIG. 1 or collar 18 as shown in FIG. 2. If it is considered desirable to introduce more than one nonaqueous solvent solution to the aqueous gelatin composition, this can be done by providing more than one inlet to the collar if a setup such as illustrated in FIG. 2 is used or more than one suction tube may empty into the inlet sleeve of shell 4 if the arrangement is as illustrated in FIG. 1.

The process in accordance with our invention is carried out by introducing the nonaqueous solvent solution into the inlet sleeve of the shell of the agitator submerged below the surface of the aqueous gelatin solution. Incorporation of the nonaqueous material into the gelatin solution is preferably accompanied by rotating the agitator at speeds between 400 and 3,600 rpm. and preferably between 750 and 2,000 rpm. Flow rates of the addenda solution may be varied over a wide range, e.g., 0.1-50 ounces per second with satisfactory results. Ordinarily the gelatin solutions to which the nonaqueous solvent solutions are added have a gelatin content of 1- -20 percent, although here again the concentration of the gelatin solution is a matter of selection for the individual operator. The flow rates of the gelatin composition can be varied by changing the impeller design, the annular effluent area, the annular inlet area or the speed of rotation or a combination of any of these.

The following examples further illustrate the invention.

EXAMPLE I Agitator 5 Va inch diameter at 1,750 rpm. Addenda feed line Ki-inch tubing Afiluent annulus inch wide Available suction 20 inches of mercury Also added is a solution of antifoggant in acetone added at the same rate. The emulsion is filtered and coated. The defect index of the composition is 1 as compared to a defect index of 5 where the same materials are added to photographic emulsion by adding to the surface of the emulsion while being stirred.

The following example illustrates the advantages obtained when the aspirating agitator is used for the addition of an aqueous solution of an acid to a silver halide gelatin emulsion.

EXAMPLE 2 A silver bromoiodide gelatin is prepared as described in example I. An aqueous solution of 2.5N sulfuric acid is added at the rate of about 1 ounce per second to the emulsion in an amount of about cc. per pound of emulsion using the aspirating agitator described in example 1. The emulsion is filtered and coated as described in example 1. The defect index of the coating is considerably lower than the defect index of a similar coating made from an emulsion where the acid solution is added to the photographic emulsion by the conventional procedure wherein the acid solution is added to the-surface of the emulsion while the emulsion is being stirred.

In the photographic art it is frequently necessary to add various types of solutions to aqueous hydrophilic colloid solutions especially to silver halide photographic emulsions which contain a hydrophilic colloid as a carrier for the silver halide crystals. For instance, sensitizing dyes and antifoggants are commonly added in the form of their solutions in organic solvents. The solvents are prone'to cause formation of coagulated particles in the hydrophilic colloid solution. Aqueous solutions of hardeners are commonly added to the hydrophilic colloid solutions. Temporary high concentrations of hardeners may cause overhardening of a portion of the hydrophilic colloid to produce'insoluble particles. It is often desirable to add acid to hydrophilic colloid solutions particularly photographic emulsions to impart a desired pl-l. Frequently such hydrophilic colloid solutions contain gelatin derivatives or other polymeric vehicles which are sensitive to an acid pH; hence, unless care is used in the addition of the acid or alkali to the colloid solution, some precipitation of the colloid may occur.

Samples of hydrophilic colloids which may be used alone or in mixtures with gelatin are:

1. Cellulose ether esters of the type described in Kodak U.S.

Pat. No. 2,725,293, e.g., cellulose ether phthalate.

2. Carboxymethyl proteins of the type described in Kodak U.S. Pat. No. 3,011,890.

3. Dibasic acid derivatives of gelatin as described in Kodak U.S. Pat. No. 2,614,928.

4. Polyvinyl pyrrolidones of the type described in British Pat. No. 867,899.

5. Polyacrylamides of the type described in U.S. Pat. No.

6. Acrylate-acrylic acid copolymers of the type described in U.S. Pat. No. 3,062,674.

7. Carboxyhydroxyethyl cellulose of the type described in Kodak U.S. Pat. No. 3,003, 878.

8. Carboxylated polyvinyl acetals of the type described in Kodak U.S. Pat. No. 3,003,879.

9. Dibasic acid esters of polyvinyl alcohol as described in Kodak U.S. Pat. No. 3,000,741.

10 Polyvinyl alcohol.

The invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and in the appended claims.

We claim:

1. An aspirator adapted to the mixing of liquids which comprises a rotatable shaft having at one end a propeller agitator composed of blades encased in a shell so as to form upon rotation a confined zone of differential pressure, inlet means for introducing by aspiration into the interior of said shell a liquid in bulk amount, inlet means for introducing by aspiration into the interior of said shell, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount, and said shell and propeller agitator being in relationship with means for restricting the outlet for the confined zone within the shell to approximately the form of an annulus.

2. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means, means positioned at the larger end of said funnelshaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing by aspiration into the interior of said shell, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

3. A mixing apparatus according to claim 2 wherein said confining means are in the shape of a truncated cone.

4. A mixing apparatus according to claim 2 wherein said confining means has a diverging tubular shape.

5; A mixing apparatus according to claim 2 wherein the confining means contain cylindrical tubular sections but the overall macroscopic shape of the confining means is a funnelshaped, diverging wall, tubular confining means.

6. A mixing apparatus according to claim 2 wherein said means to form an annular opening'is located in abutting relationship to said blades.

7. A mixing apparatus according to claim 2 wherein a discharge outlet of said means for. introducing said second liquid is located on the outside of the confining means but within the inlet fiow path of the means for introducing bulk amounts into said confining means.

8. A mixing apparatus which comprises a rotatable shaft having atone end a propelleragitator composed of blades, I v

said blades encased in a funnel-shaped tubular confining means, disc means positioned at the larger end of said funnelshaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

9. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means, means positioned at the larger end of said funnelshaped confining means to forrnan annular opening, conic sectional opening means at the converging end of said confining means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

10. A mixing apparatus according to claim 9 wherein said propeller shaft is located within the conic sectional opening at the converging end of said confining means.

11. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in and attached to a funnel-shaped tubular confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means'for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

12. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means wherein said blades and said propeller shaft rotate relative to said confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.

13. The mixing apparatus according to claim 12 wherein the confining means is provided with vanes disposed internally and substantially parallel to the propeller shaft. 

2. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing by aspiration into the interior of said shell, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.
 3. A mixing apparatus according to claim 2 wherein said confining means are in the shape of a truncated cone.
 4. A mixing apparatus according to claim 2 wherein said confining means has a diverging tubular shape.
 5. A mixing apparatus according to claim 2 wherein the confining means contain cylindrical tubular sections but the overall macroscopic shape of the confining means is a funnel-shaped, diverging wall, tubular confining means.
 6. A mixing apparatus according to claim 2 wherein said means to form an annular opening is located in abutting relationship to said blades.
 7. A mixing apparatus according to claim 2 wherein a discharge outlet of said means for introducing said second liquid is located on the outside of the confining means but within the inlet flow path of the means for introducing bulk amounts into said confining means.
 8. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means, disc means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.
 9. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of Blades, said blades encased in a funnel-shaped tubular confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, conic sectional opening means at the converging end of said confining means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.
 10. A mixing apparatus according to claim 9 wherein said propeller shaft is located within the conic sectional opening at the converging end of said confining means.
 11. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in and attached to a funnel-shaped tubular confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.
 12. A mixing apparatus which comprises a rotatable shaft having at one end a propeller agitator composed of blades, said blades encased in a funnel-shaped tubular confining means wherein said blades and said propeller shaft rotate relative to said confining means, means positioned at the larger end of said funnel-shaped confining means to form an annular opening, means for introducing into the interior of said confining means a liquid in bulk amounts and means for introducing into the interior of said confining means, at a point at which the liquid in bulk amount enters, a second liquid in an amount comparatively small relative to the liquid in bulk amount.
 13. The mixing apparatus according to claim 12 wherein the confining means is provided with vanes disposed internally and substantially parallel to the propeller shaft. 